Process of oxidizing gases



UNITED T T S PATENT oar-IC i am: a. mum, or NEW YORK, nfx

raocnss or oxmrzmo easns.

To all whom wit racy concem:

Be it known that I, RALPH H. MoKma, a

citizen of the United States, and a resident of New York in the county of New York and State of lTew York, have invented certain new and-useful Improvements in Processes of Oxidizin Gases, of which the fol-,

' lowing is a speci cation.

This invention relates to novel processes of oxidizing gases and contemplates the use,

.in the above mentioned processes of. a catalytic'material not heretofore used for this or any similar purpose. v

The object of the invent1on 1s to prov de a cheap, convenient and effective process by which gases generally may be oxidized, and

one of the principal objects is to provide a process whereby nitrogen which has been initially oxidized may be rapidly brought to a higher de ree of oxidation.

As is wel known nitric oxid (NO) may i be produced in a variety of ways such as by the oxidation of ammonia, by the action of the electric arc on gas mixtures containin nitrogen and oxy n as in the Birkelan Eyde and Schoe err processes, or by subjecting oxygen-nitrogen mixtures to hightemlperatures obtained by the combustion of fue with or without explosion. When in any of the above processes the object desired is the production of nitric acid, the nitric oxid is further oxidized to nitrogen eroxid (N0 or N 0,). In the presence 0 water, under suitable conditions, nitrogen peroxid forms nitric acid.

In the reaction of nitrogen peroxid upon ..water, some nitric oxid is formed, the reaction apparently taking place as follows An oxidation of the nitric oxid so produced is thus rendered necessary, this oxidation being followed by a treatment with water to absorb the nitrogen peroxid, and the oxidizing and ,absorbing steps are continued alternately until substantially complete conversion to nitric acid is efi'ected In practice the water is usually introduced as dilute nitric acid.

It has been shown that certain catalysts;

, promote the oxidation of nitric'oxid and I ave found that a particularly. effective and satisfactory catalyst for this purpose is hy dratedsilica gel. If, for example, a' solu'-' tion of watergl'ass is acid fied. and. the re-;

Renewed February 10, 1021. Serial Specification 0! Letters Patent. Patented Sept 1921. 4

- Io Drawing. a umioil filed s urs, 1919, Serial No. 281,740:

sulting silicic acidc llected and washed and i i dried at somewhat elevated temperatures, there is produced a material which is admirably adapted to serve as a catalyst .in the above process. When gases containing nitric oxid and a sufiicient quantity of oxygen are passed through a space containing the catalyst, a substantially com lete conversion to nitrogen peroxid is rapid y efi'ected. In one .form of my invention, the gas stream flows through a series of chambers in which it is alternately exposed first to the action of silica gel and then to. the absorbing action of water or, dilute nitric acid, but I do .not wlsh to be limited to such a series of steps nor to any particular order of oxidizing and absorbing o erations. Since the oxidat1on of NO to O is exothermic, there will be no cooling of the gases in contact with the catalyst and hence no deposition of wa- The gases ter in the catalytic chamber. should be reasonably dust-free to avoid contamination of the catalyst.

The hydrated silica gel may be used alonea sufiicient amount of oxygen in contact with a catalyst comprisinghydrated silica gel, substantially as described.

2. The processof oxidizing gases which comprises passing said gases together with a suflicient amount of oxygen in contact with a catalyst comprising sensibly dry hydrated silica gel, substantially as described.

3. The process which comprises passing a gas stream containing a lower gaseous oxid capable of forming a higher oxid, together with a sufficient amount of oxygen to effect 'such oxidation, in contact with a catalyst comprising hydrated silica gel, substantially as described.

4. The process which comprises passing a gas stream containing a lower gaseous oxid capableof forming a higher oxid, together with a sufficient amount of oxygen to effect 6. The process which comprises passing a 10 such oxidation, in contact with a catalyst gas stream containing nitric oxid together comprising sensibly dry hydrated silica gel, with a sufiicient quantity of oxygen in consubstantially as descrihed. tact with a catalyst comprising sensibly dry 5. The processwhich comprises passing a hydrated silica gel, substantially as degas stream containing nitric oxid together scribed. 15

with a sufiicient quantity of oxygen in con- In testimony whereof-I afiix my signature. tact with a catalyst comprising hydrated v silica gel, substantially as described. RALPH H. MoKEE. 

